MEDIUM: list: Separate "locked" list from regular list.

Instead of using the same type for regular linked lists and "autolocked"
linked lists, use a separate type, "struct mt_list", for the autolocked one,
and introduce a set of macros, similar to the LIST_* macros, with the
MT_ prefix.
When we use the same entry for both regular list and autolocked list, as
is done for the "list" field in struct connection, we know have to explicitely
cast it to struct mt_list when using MT_ macros.
diff --git a/include/proto/listener.h b/include/proto/listener.h
index 24a01b2..b245d6e 100644
--- a/include/proto/listener.h
+++ b/include/proto/listener.h
@@ -58,7 +58,7 @@
 int disable_all_listeners(struct protocol *proto);
 
 /* Dequeues all of the listeners waiting for a resource in wait queue <queue>. */
-void dequeue_all_listeners(struct list *list);
+void dequeue_all_listeners(struct mt_list *list);
 
 /* Must be called with the lock held. Depending on <do_close> value, it does
  * what unbind_listener or unbind_listener_no_close should do.